An off-line power converter can be implemented using an integrated circuit power factor controller to provide power factor correction to off-line appliances. Power factor correction helps to boost the efficiency of power transfer to the load and to reduce electromagnetic interference (EMI). The integrated circuit drives power factor correction stages and can operate in a critical conduction mode to provide light load operation control and other useful control and safety features. However it would be desirable to decrease the cost of off-line power converters while retaining the power factor correction and safety features of existing designs.
The use of the same reference symbols in different drawings indicates similar or identical items.